JP2004296535A - Semiconductor device, its fabricating process, ferroelectric memory, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable semiconductor device in which the resistance of an interconnect line can be prevented from increasing even in a stack structure, and to provide its fabricating process. <P>SOLUTION: First conductive barrier layers (131, 132) for preventing diffusion of gas components are provided in a through hole (H4) made through interlayer insulation films (117, 124) formed on the underlayer surface (114). A second insulating barrier layer (116) for preventing diffusion of gas components is provided at the interface of the underlayer surface (114) and the interlayer insulation film on the outside of the through hole (H4). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ferroelectric memory, and more particularly, to a structure of a ferroelectric memory having a small memory cell area and suitable for high-density integration, and a method of manufacturing the same.
[0002]
[Prior art]
A ferroelectric memory has features such as a writing speed comparable to that of an SRAM and a large number of rewritable times, and has attracted attention as a next-generation nonvolatile memory following a flash EEPROM. In order to increase the degree of integration of the memory cells, a stack structure in which a ferroelectric capacitor is formed immediately above a transistor, such as a 1T1C type, is considered preferable. Tungsten plugs are often used to connect bit lines and word lines that cross at different levels in the vertical direction.
[0003]
When forming a tungsten plug, hydrogen (H ₂ ) is used as a reducing agent to remove fluorine (F) from WF ₆ used when depositing tungsten (W). When this hydrogen diffuses into the ferroelectric in the ferroelectric capacitor, the remanent polarization characteristics in the ferroelectric layer are extremely deteriorated, and the memory retention function is not exhibited. For this reason, techniques for preventing the ferroelectric from being deteriorated by hydrogen have been developed. For example, Japanese Patent Application Laid-Open No. 2002-141482 discloses a technique in which a hydrogen barrier layer for preventing the permeation of hydrogen is provided on the inner surface of a tungsten plug and then tungsten is filled (Patent Document 1). The hydrogen barrier layer can prevent the ferroelectric from being deteriorated when the tungsten plug is formed.
[0004]
[Patent Document 1]
JP, 2002-141482, A [Problems to be solved by the invention]
However, in the case of a stacked ferroelectric memory, an insulating film may be formed further above the tungsten plug, or another ferroelectric capacitor may be provided and oxygen annealing may be performed. In some cases, the plug was adversely affected. That is, tungsten is very easily oxidized, and when oxidized, it has a high resistance and does not function as a conduction path.
[0005]
Therefore, an object of the present invention is to provide a highly reliable semiconductor device capable of preventing an increase in wiring resistance even in a stack structure, and a method for manufacturing the same.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a method in which a first barrier layer having conductivity for preventing diffusion of a gas component is provided in a through hole provided in an interlayer insulating film formed on a base surface. In addition, a second barrier layer having an insulating property for preventing diffusion of a gas component is provided outside the through hole at an interface between the base surface and the interlayer insulating film.
[0007]
According to the above configuration, since the first barrier layer has conductivity, electric conduction in the stack structure can be secured between the first barrier layer and the underlying surface in contact with the first barrier layer. On the other hand, the gas component invading from the upper layer side is blocked by the first barrier layer portion for the through hole which is the conductive path, and the second barrier layer is formed for the portion other than the through hole which is not the conductive path. Is prevented. Therefore, since the gas component is completely blocked from passing through the base surface and below, it is possible to effectively prevent the gas component from affecting the lower layer of the base surface.
[0008]
Here, in the present invention, the “interlayer insulating film” is not limited in its type, but generally refers to a film formed to fill a space between a wiring, a semiconductor, and a ferroelectric of a semiconductor device, and may be a single layer or a plurality of layers. Regardless.
[0009]
The “base surface” is a surface serving as a base on which the layer structure is formed, and includes a case where a layer structure that causes a problem when a gas component permeates is formed. For example, in a ferroelectric memory, a base surface becomes a part of a ferroelectric capacitor.
[0010]
The “through hole” is a contact hole provided for connecting elements and wirings arranged in the stacking direction, and is a through hole, but its shape is not limited.
[0011]
A “gas component” is a gas and is particularly meaningful when it can affect any layer structure. Examples of such a gas component include oxygen and hydrogen.
[0012]
The present invention provides an interlayer insulating film having a through hole formed on a base surface, a first oxygen barrier layer formed at least on a wall surface and a bottom surface of the through hole and having conductivity to prevent diffusion of oxygen, And a conductive material filled in the hole.
[0013]
According to the above structure, while the oxygen barrier layer is conductive, it contributes to the electrical conduction in the stack structure, while preventing the transmission of oxygen from one to the other, so that even if oxygen is generated during the formation of the upper layer, for example, The oxygen can be prevented from moving to the lower layer side. Therefore, even if a layer whose characteristics are deteriorated by oxygen is present under the base surface, no trouble occurs.
[0014]
Here, in the present invention, the “bottom surface” refers to an opening surface on the lower layer side.
[0015]
The “oxygen barrier layer” means a layer having a structure capable of blocking the passage of oxygen, but may be a layer capable of blocking the passage of other elements. As such a barrier layer, TiAlN is particularly preferable because it has a dense structure and effectively prevents the passage of oxygen. In addition, titanium (Ti), titanium nitride (TiN), and the like can be used as the oxygen barrier layer.
[0016]
The "conductive material" may be any substance that has electrical conductivity and can be filled in a fine through hole, and a metal such as tungsten, aluminum, or an alloy thereof can be used. In particular, tungsten can be filled in a hole having a large aspect ratio (thickness with respect to the opening diameter), and thus is suitable as a filler for a contact hole in a semiconductor device which has a high density. Tungsten has the property of being easily oxidized, but according to the present invention, the oxygen barrier layer effectively blocks the oxidation, so that the oxidation of tungsten can be prevented.
[0017]
Here, diffusion of hydrogen formed at least in at least one of between the wall surface and the bottom surface of the through-hole and the first oxygen barrier layer or between the first oxygen barrier layer and the conductor is prevented. It is preferable to further include a first hydrogen barrier layer having a conductive property.
[0018]
According to the above structure, while the hydrogen barrier layer is conductive, it contributes to the electrical conduction in the stack structure, while preventing the permeation of hydrogen from one to the other. Can also prevent the hydrogen from moving to the lower layer side. Therefore, even if there is a layer whose characteristics are deteriorated by hydrogen under the base surface, no trouble occurs.
[0019]
Here, the “hydrogen barrier layer” means a layer having a structure capable of blocking passage of hydrogen, but may be a layer capable of blocking passage of other elements. As such a barrier layer, a composition in which a metal is Ir, Pt, Ru, Re, Ni, Co, or Mo in a composition of a predetermined metal oxide or metal (M) -Si-N is preferable, and in particular, IrOx, IrSiN and PtSiN are preferable because they have a dense structure and effectively prevent the passage of hydrogen.
[0020]
Here, a second hydrogen barrier layer having an insulating property and formed between the base surface and the interlayer insulating film and surrounding the outside of the through hole may be further provided. According to this structure, although there is no conductivity around the through hole, the hydrogen barrier prevents the permeation of hydrogen, so that the flow of hydrogen between the upper layer and the lower layer can be completely prevented.
[0021]
Note that examples of the insulating hydrogen barrier layer include metal oxides represented by metal (M) -Ox, for example, AlOx and TiOx.
[0022]
Here, it is preferable to further include an insulating second oxygen barrier layer formed between the base surface and the interlayer insulating film so as to surround the outside of the through hole. According to this structure, although there is no conductivity around the through hole, the oxygen barrier prevents the permeation of oxygen, so that the flow of oxygen between the upper layer and the lower layer can be completely prevented.
[0023]
Note that examples of the oxygen barrier layer having an insulating property include a metal oxide represented by metal (M) -Ox, for example, AlOx or TiOx.
[0024]
The present invention provides a step of providing a through hole in an interlayer insulating film formed on a base surface, and a step of forming a first oxygen barrier layer having conductivity to prevent diffusion of oxygen at least on a wall surface and a bottom surface of the through hole. Filling the through hole with a conductive material.
[0025]
According to the above process, the oxygen barrier layer is electrically conductive and contributes to the electric conduction in the stack structure, while preventing the transmission of oxygen from one to the other. The oxygen can be prevented from moving to the lower layer side. Therefore, even if a layer whose characteristics are deteriorated by oxygen is present under the base surface, no trouble occurs.
[0026]
Here, at least one of the interface between the wall surface and the bottom surface of the through-hole and the first oxygen barrier layer or the interface between the first oxygen barrier layer and the conductive material has the first hydrogen having conductivity for preventing diffusion of hydrogen. It is preferable that the method further includes a step of forming a barrier layer.
[0027]
According to the above process, the hydrogen barrier layer is electrically conductive and contributes to the electric conduction in the stack structure, while preventing the transmission of hydrogen from one to the other. Can also prevent the hydrogen from moving to the lower layer side. Therefore, even if there is a layer whose characteristics are deteriorated by hydrogen under the base surface, no trouble occurs.
[0028]
Here, the method further includes a step of forming a second oxygen barrier layer having an insulating property at an interface between the base surface and the interlayer insulating film. In the step of providing a through hole in the interlayer insulating film, the second oxygen barrier layer communicates with the second oxygen barrier layer. It is preferable to form the through-hole by pressing. According to this structure, although there is no conductivity around the through hole, the oxygen barrier prevents the permeation of oxygen, so that the flow of oxygen between the upper layer and the lower layer can be completely prevented.
[0029]
Here, the method further includes a step of forming a second hydrogen barrier layer having an insulating property at an interface between the base surface and the interlayer insulating film. In the step of providing a through hole in the interlayer insulating film, the second hydrogen barrier layer communicates with the second hydrogen barrier layer. It is preferable to form the through-hole by pressing. According to this step, although there is no conductivity around the through hole, the hydrogen barrier prevents the permeation of hydrogen, so that the flow of hydrogen between the upper layer and the lower layer can be completely prevented.
[0030]
The present invention is also a ferroelectric memory including the semiconductor device of the present invention, wherein the base surface is formed by a part of the ferroelectric capacitor, and the ferroelectric memory formed by the method of manufacturing a semiconductor device of the present invention. It is also memory. The present invention is also an electronic device provided with such a ferroelectric memory.
[0031]
According to this configuration, since the semiconductor device, the ferroelectric memory, and the electronic device have the layer structure of the present invention, the ferroelectric does not deteriorate due to hydrogen, and the reliability is high.
[0032]
Here, “electronic equipment” refers to general equipment having a certain function provided with the semiconductor device or the ferroelectric memory according to the present invention, and the configuration thereof is not particularly limited. Computers, mobile phones, video cameras, head-mounted displays, rear or front projectors, fax machines with display functions, digital camera finders, portable TVs, DSPs, PDAs, personal organizers, electronic bulletin boards, advertising notices Display and the like.
[0033]
It is more preferable that at least one of the upper electrode and the lower electrode constituting the ferroelectric capacitor is provided with a third oxygen barrier layer having conductivity. According to this structure, since the third oxygen barrier layer is in close contact with the ferroelectric capacitor, oxygen generated by the heat treatment of the ferroelectric layer and diffused outside can be prevented.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0035]
(1st Embodiment)
The first embodiment of the present invention is a ferroelectric memory having a structure as a semiconductor device of the present invention, and is also manufactured by the method of manufacturing a semiconductor device of the present invention.
[0036]
FIG. 1 shows a memory cell layer structure of the ferroelectric memory according to the first embodiment. Structurally, ferroelectric memories are classified into several types according to the number of transistors and ferroelectric capacitors included in a memory cell. In particular, the present invention is effective for a structure such as 1T1C or 1T2C in which a transistor and a ferroelectric capacitor have a laminated structure. However, FIG. 1 is merely an example of a layer structure for showing the features of the present invention, and Is not limited.
[0037]
As shown in FIG. 1, in the present ferroelectric memory 1a, a transistor T is formed on a substrate 100 made of silicon or the like for forming a semiconductor element. The transistors are separated by an element separation layer 101. A diffusion region 102 serving as a source / drain region of a transistor is formed in a substrate 100. A gate electrode made of polysilicon, SiW, or the like is surrounded on a channel region of the substrate 100 by a sidewall 104 via a gate insulating film 103. 105 are formed. The gate electrode 105 forms a word line W in the memory cell array.
[0038]
On the substrate 100, a first interlayer insulating film 106 is formed, and through holes H1 and H3 are formed so as to communicate with the second interlayer insulating film 117. In the through holes H1 and H2, a wiring layer 122 surrounded by the first oxygen barrier layers 121 and 123 is formed to form a plate line.
[0039]
A ferroelectric capacitor C is formed on the first interlayer insulating film 106. A second oxygen barrier layer 110 is formed below the ferroelectric capacitor C, and a third oxygen barrier layer 114 is formed above the ferroelectric capacitor C. The ferroelectric capacitor C includes a lower electrode 111, a ferroelectric layer 112, and an upper electrode 113. A first hydrogen barrier layer 116 is entirely formed on the first interlayer insulating film 106 and the third oxygen barrier layer 114. On the first hydrogen barrier layer 116, a second interlayer insulating film 117 is formed.
[0040]
In the second interlayer insulating film, a through hole H4 is formed penetrating directly to the upper electrode 113 of the ferroelectric capacitor C. Further, a through hole H2 is formed penetrating to the lower electrode 111, and the wiring layer 122 is connected. Also, a through hole H5 reaching the wiring layer 122 is provided.
[0041]
A fourth oxygen barrier layer 131 and a second hydrogen barrier layer 132 are formed on the wall surface and the bottom surface of the through hole H4, and the inside is filled with a second conductor 133. Further, a through hole H5 is formed in the second interlayer insulating film 117 so as to penetrate to the wiring layer 122.
[0042]
A wiring layer 142 corresponding to the bit line B is laid substantially orthogonal to the word line 105 on the second interlayer insulating film, and a fifth oxygen barrier layer 141 and a sixth oxygen barrier layer 143 are formed on the surface thereof. ing. The bit line B is electrically connected to the upper electrode 113 of the ferroelectric capacitor C via the through hole H4, and is electrically connected to the wiring layer 122.
[0043]
Further, individual layers according to the present invention will be specifically described. A known layer structure can be applied to the structure relating to the substrate 100 and the transistor T.
[0044]
The first interlayer insulating film 106 is made of SiO ₂ or the like. In the stack structure of the ferroelectric memory, the thickness is determined according to a distance to be kept apart from a ferroelectric capacitor to be subjected to a heat treatment in manufacturing. If the thickness is too small, the heat treatment at the time of forming the ferroelectric capacitor has an adverse effect on the transistor. If the thickness is too large, it is difficult to secure perfect conduction even with a tungsten plug.
[0045]
The first oxygen barrier layers 121 and 123 are made of TiN or the like, and also function as adhesion layers for improving the adhesion between the wiring layer 122 and the insulating film. The wiring layer 122 is made of a normal wiring material having conductivity and easy to manufacture, for example, AlCu.
[0046]
The second oxygen barrier layer 110 and the third oxygen barrier layer 114 provided on the lower layer and the upper layer of the ferroelectric capacitor C are mainly made of a conductive material capable of blocking the passage of oxygen. It may be one that can block the passage of elements. As such a barrier layer, a metal oxide or a metal nitride is suitable. In particular, TiAlN has a dense structure and is preferable for effectively preventing the passage of oxygen.
[0047]
The ferroelectric capacitor C has a known layer structure. For example, the upper electrode 111 and the lower electrode 113 are formed of a highly reliable metal material, for example, platinum (Pt) or iridium (Ir), but may have a multilayer structure with Ti in consideration of adhesion and the like. Good. The ferroelectric layer 112 is made of a ferroelectric ceramic material having polarization characteristics suitable for a memory, for example, lead zirconate titanate (PZT), strontium bismuth tantalate (SBT), bismuth titanate (BIT), or the like. A material exhibiting a high amount of remanent polarization can be used.
[0048]
The first hydrogen barrier layer 116 according to the present invention has an insulating property and is formed so as to cover the ferroelectric capacitor C and cover the interface between the first interlayer insulating film 106 and the second interlayer insulating film 117. . The hydrogen barrier layer prevents the ferroelectric material of the ferroelectric capacitor C from being reduced by hydrogen generated when a conductive material such as tungsten used for forming the through hole H4 is generated, and prevents the remanent polarization characteristic from changing. Examples of the insulating hydrogen barrier layer include metal oxides represented by metal (M) -Ox, for example, AlOx and TiOx. These materials also have oxygen barrier performance. If the thickness of the insulating hydrogen barrier layer is too small, the barrier properties will be reduced, so that the thickness is appropriately determined.
[0049]
The second interlayer insulating film 117 can be considered in the same manner as the first interlayer insulating film 106. A fourth oxygen barrier layer 131 and a second hydrogen barrier layer 132 are formed on the wall and bottom of the through hole H4 provided in the interlayer insulating film.
[0050]
The fourth oxygen barrier layer 131 according to the present invention is mainly composed of a conductive material capable of blocking the passage of oxygen, but may of course be a material capable of blocking the passage of other elements. As such a barrier layer, a metal oxide or a metal nitride is suitable. In particular, TiAlN has a dense structure and is preferable for effectively preventing the passage of oxygen. If the thickness of the oxygen barrier layer is too large, the space filled with the conductive material to be filled becomes small, and sufficient conductivity cannot be secured. If the thickness is too small, a sufficient barrier effect cannot be obtained.
[0051]
The second hydrogen barrier layer 132 is mainly made of a conductive material capable of blocking the passage of hydrogen, but may of course be a material capable of blocking the passage of other elements. As such a barrier layer, a metal oxide or a metal nitride is suitable, and here, IrOx is used. If the thickness of the oxygen barrier layer is too large, the space filled with the conductive material to be filled becomes small, and sufficient conductivity cannot be secured. If the thickness is too small, a sufficient barrier effect cannot be obtained.
[0052]
As a material of the second conductor 133, a metal having electrical conductivity and capable of filling a fine through hole, for example, tungsten (W), aluminum (Al), or an alloy thereof can be used. In particular, tungsten can be filled in a hole having a large aspect ratio (thickness with respect to the opening diameter), so that it is suitable as a filler for a contact hole in a semiconductor device having a high density. Have been. Although tungsten has a disadvantage that it is easily oxidized, according to the present invention, since the second hydrogen barrier layer 132 effectively blocks hydrogen, it is possible to prevent the ferroelectric layer 112 from being reduced and the polarization characteristics from deteriorating. Can be done.
[0053]
For the wiring layer 142, a normal wiring material having conductivity and easy to manufacture, for example, AlCu is used. A fifth oxidation barrier layer 141 is formed on the surface of the wiring layer 142 to prevent oxygen that has passed through the first hydrogen barrier layer 116 from migrating to the ferroelectric capacitor C.
[0054]
In the above layer structure, when the word line 105 is selected and a voltage is applied between the bit line B and the plate line, '1' or '0' is written into the ferroelectric capacitor according to the polarity. When the word line W is selected as the plate line and the bit line is fixed at a predetermined potential, a voltage corresponding to the polarization state is generated. By detecting this, the bit stored in the ferroelectric capacitor is detected. The information can be read.
[0055]
Here, the inside of the through hole H4 is filled with tungsten as the second conductive material 133, but is oxidized by oxygen generated by an upper layer forming step, for example, oxygen annealing or formation of an interlayer insulating film in forming a ferroelectric capacitor. Easy to do. Although the fourth oxygen barrier layer 141 and the fifth oxygen barrier layer 143 directly shield oxygen diffused from the ferroelectric layer or the interlayer insulating film, the oxygen sneaking from the periphery to the side surface of the through hole H4 does not I can't prevent it. According to this embodiment, since the fourth oxygen barrier layer 131 is formed on the wall surface of the through hole H4, oxygen from the surroundings is also shielded, thereby preventing the second conductor 133 from being oxidized. .
[0056]
Hydrogen generated during the production of tungsten reduces and deteriorates the ferroelectric layer 112 of the lower ferroelectric capacitor C. According to the present embodiment, the hydrogen flowing from the plug bottom surface to the ferroelectric capacitor C is shielded while the conductive second hydrogen barrier layer 132 ensures conduction. In addition, the first hydrogen barrier layer 116 having an insulating property blocks hydrogen from the upper layer toward the side surface of the ferroelectric capacitor C. Therefore, the ferroelectric capacitor can be protected from hydrogen.
[0057]
(Manufacturing process)
Next, a method of manufacturing the ferroelectric memory 1a according to the first embodiment will be described. 2 and 3 are cross-sectional views showing a manufacturing process according to this embodiment.
[0058]
First, a transistor T is formed on a silicon substrate 100 by applying a known semiconductor process technique, and then a first interlayer insulating film 106, a second oxygen barrier layer 110, and a lower electrode 111 are formed (ST1). The transistor T functions as a switching element of the ferroelectric capacitor C. The interlayer insulating film 106 is formed to a predetermined thickness on the silicon substrate 100 by applying a known oxide film forming method, for example, a thermal oxidation method.
[0059]
Next, the second oxygen barrier layer 110 and the lower electrode 111 of the ferroelectric capacitor are formed (ST2). As a method for manufacturing these laminated structures, any method may be used as long as it is suitable for forming a metal thin film or a metal nitride film and can form a thin film with a uniform thickness to some extent. It is possible to choose. For example, various vapor deposition methods such as CVD (including MOCCVD, low pressure CVD, and ECR-CVD), vapor deposition, molecular beam deposition (MB), sputtering, ion plating, and PVD, electroplating, and immersion plating ( Dipping), various plating methods such as electroless plating method, coating methods such as Langmuir-Blodgett (LB) method, spin coating method, spray coating method, roll coating method, various printing methods, transfer method, ink jet method, powder jet method And so on. Two or more of these methods may be combined. Here, the second oxygen barrier layer 110 and the lower electrode 111 are formed by a sputtering method or an evaporation method. The resist 118 is patterned into the shape of the lower electrode by photolithography.
[0060]
Next, after patterning the second oxygen barrier layer 110 and the lower electrode 111, the ferroelectric layer 112 and the upper electrode 113 of the ferroelectric capacitor are formed (ST2). In order to obtain a predetermined crystalline state, the ferroelectric layer 112 is formed by forming a crystal of the ferroelectric ceramic material by a sol-gel method, a MOD (Metal Organic Deposition) method, a sputtering method, a CVD method, or the like. For example, when using a sol-gel method, a precursor solution containing a ferroelectric ceramic material is applied to a predetermined thickness, for example, a thickness of about 120 nm. Then, it is possible to form a thin film in a uniform and good crystalline state by growing crystals by drying, degreasing, and firing in a heat treatment step in which the temperature and time are adjusted. In this heat treatment step, oxygen is generated and diffuses in the layer structure. However, in the present embodiment, since the oxygen barrier layer does not allow oxygen to permeate, oxidation of the conductive material can be effectively prevented. After the crystallization of the ferroelectric layer 112 is completed, Pt is further formed as the upper electrode 113 by a known thin film forming technique, for example, a sputtering method or a vapor deposition method. Then, TiAlN is formed as the third oxygen barrier layer 114 by the same method. Next, the resist 115 is patterned into a shape of the ferroelectric capacitor C by a photolithography method by applying a photolithography method.
[0061]
Next, the third oxygen barrier layer 114 is first patterned using the resist 115 as a mask. Next, using the third oxygen barrier layer 114 as a mask, the upper electrode 113 and the ferroelectric layer 112 are etched (ST3). As an etching method for the layer structure of the ferroelectric capacitor C, dry etching (such as plasma etching) that can remove different layers in a similar shape can be applied. Next, a first hydrogen barrier layer 116 is formed on the surfaces of the ferroelectric capacitor C and the first interlayer insulating film 106. The hydrogen barrier layer 116 is formed with a predetermined thickness, for example, about 40 nm by using the above material and applying a sputtering method or an evaporation method.
[0062]
A second interlayer insulating film 117 is formed thereon, through holes H1 to H3 are provided, and a connection wiring between the ferroelectric capacitor C and the transistor T and a wiring serving as a plate line are formed (ST4). The second interlayer insulating film 117 is formed in the same manner as the first interlayer insulating film. The through holes H1 to H3 are provided by applying a known technique, for example, electric discharge machining for fine holes, etching, and drilling. A predetermined conductive material, for example, AlCu, is used for the wiring layer 122, and a material for improving the adhesion to the insulating film, for example, Pt, Au, W, Ta, Mo, Al, Cr, Ti, or the like is used for the adhesion layers 121 and 123. Metals such as alloys containing these as main components are used. For example, when Ti, TiN, or a laminated structure thereof is used for the adhesion layer, it can be said that such a composition itself has a certain degree of oxygen barrier performance, which is preferable. The wiring layer 122 and the adhesion layers 121 and 123 are formed by a known technique, for example, a sputtering method or an evaporation method. After that, a third interlayer insulating film 124 is formed in the same manner as the interlayer insulating film.
[0063]
In order to form a plug connected to the ferroelectric capacitor C, a through hole H4 is formed through the third interlayer insulating film 124, the second interlayer insulating film 117, and the first hydrogen barrier layer 116 (ST5). If the through hole H4 is formed in a tapered shape, a filled conductive material is easily formed. Therefore, the angle of the side wall of the through hole H4 with respect to the substrate surface is set to, for example, 80 degrees or less. The underlying surface of the through hole H4 is the third oxygen barrier layer 114.
[0064]
The fourth oxygen barrier layer 131, the second hydrogen barrier layer 132, and the second conductor 133 are stacked in the through hole H4 (ST6). The fourth oxygen barrier layer 131 is mainly composed of a conductive material capable of blocking the passage of oxygen, but may of course be a material capable of blocking the passage of other elements. As such a barrier layer, a metal oxide or a metal nitride is suitable. In particular, TiAlN has a dense structure and is preferable for effectively preventing the passage of oxygen. The thickness of the oxygen barrier layer is determined according to the diameter of the through hole H4. If the thickness is too large, the second conductive material 133 is difficult to be filled, and the reliability is impaired. If the thickness is too small, the oxygen barrier effect is reduced.
[0065]
The second hydrogen barrier layer 132 is mainly made of a conductive material capable of blocking the passage of hydrogen, but may of course be a material capable of blocking the passage of other elements. As such a barrier layer, a metal oxide or a metal nitride is suitable. In particular, IrOx has a dense structure and is preferable for effectively preventing the passage of hydrogen. The thickness of the hydrogen barrier layer is determined according to the diameter of the through hole H4. If the thickness is too large, the second conductive material 133 is difficult to be filled, and the reliability is impaired. If the thickness is too small, the hydrogen barrier effect is reduced. The second conductive material is laminated by a sputtering method or a vapor deposition method until the second conductive material 133 is thick enough to reliably fill the through holes H4 and H5.
[0066]
Thereafter, an etch-back process is performed until the surface of the third interlayer insulating film 124 is exposed, so that the opening surfaces of the through holes H4 and H5 and the insulating film surface are formed on the same surface (ST7). By this step, a structure as a tungsten plug was formed in which the side walls and the bottom surface were surrounded by the second hydrogen barrier layer 132 and the fourth oxygen barrier layer 131.
[0067]
Thereafter, as shown in FIG. 1, in order to form a wiring corresponding to the bit line B, a fifth oxygen barrier layer 141 is formed by TiN or the like by applying a sputtering method or an evaporation method, and a wiring layer is formed by AlCu or the like. By forming 142 and forming the sixth oxygen barrier layer 143, a layer structure of the memory cell is formed.
[0068]
According to the first embodiment, while the second hydrogen barrier layer 132 is conductive and contributes to the electric conduction in the stack structure, it blocks the permeation of hydrogen from one to the other. Thus, even if hydrogen is generated, it is possible to prevent the hydrogen from moving to the lower ferroelectric capacitor C. Therefore, it is possible to prevent the polarization characteristics of the ferroelectric capacitor C from being reduced by the reducing action of hydrogen.
[0069]
Further, according to the first embodiment, although there is no conductivity around the through-hole H4, the first hydrogen barrier 116 prevents the permeation of hydrogen. Therefore, even if hydrogen is generated in the process of forming a tungsten plug, for example, Hydrogen can be prevented from moving to the lower ferroelectric capacitor C. Therefore, it is possible to prevent the polarization characteristics of the ferroelectric capacitor C from being reduced by the reducing action of hydrogen.
[0070]
Further, according to the first embodiment, while the fourth oxygen barrier layer 131 and the second oxygen barrier layer 110 are conductive, they contribute to electric conduction in the stack structure, while preventing oxygen from passing from one to the other. Therefore, for example, even if oxygen is generated in the process of forming the ferroelectric capacitor or the interlayer insulating film, it is possible to prevent the oxygen from moving to the lower layer or the upper layer. Therefore, even if tungsten plugs are present above and below the ferroelectric capacitor C, they are not oxidized by oxygen to increase the resistance and hinder the conductivity. Therefore, the reliability of the ferroelectric capacitor can be improved.
[0071]
(2nd Embodiment)
The second embodiment of the present invention relates to the same ferroelectric memory as the first embodiment, but differs in that a plug is also used for the lower layer connection of the ferroelectric capacitor. Portions relating to the same structures and processes as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
[0072]
In the first embodiment, the plug structure exists only on the upper layer side of the ferroelectric capacitor C (through hole H4). However, in the second embodiment, the plug structure exists on the lower layer side of the ferroelectric capacitor C. The difference is that plug structures are also provided in the through holes H2 and H4 that contribute to the connection structure from the bit line B to the silicon substrate 100.
[0073]
FIG. 4 shows a layer structure of the ferroelectric memory 1b according to the second embodiment. As shown in FIG. 4, in the ferroelectric memory 1b, through holes H1 and H2 are formed in the first interlayer insulating film 106, and an adhesion layer 107 and a first oxygen barrier layer 108 are formed on the wall surface and bottom surface thereof. The first conductive material 109 is filled.
[0074]
The adhesion layer 107 can be used to ensure adhesion between the first conductive material 109 or the first oxygen barrier layer 108 and the insulating film 106. The material used for the adhesion layer 107 is the same as the material used for the adhesion layers 121 and 123, and the material used for the first oxygen barrier layer 108 is the same as the material used for the oxygen barrier layers 110, 114, and 131.
[0075]
The structure relating to the through holes H3 and H4 is the same as the through hole H4 of the first embodiment.
[0076]
Next, a method of manufacturing the ferroelectric memory 1b according to the second embodiment will be described. 5 and 6 are cross-sectional views showing a manufacturing process according to this embodiment.
[0077]
After forming the transistors T1 and T2 and the first interlayer insulating film 106 in the same manner as in the first embodiment (FIG. 2: ST1), through holes H1 and H2 are formed. Next, the adhesion layer 107, the first oxygen barrier layer 108, and the first conductor 109 are stacked on the wall surface and bottom surface of the through hole and on the first interlayer insulating film 106 (ST10). Here, a laminated structure of Ti and TiN is adopted as the adhesion layer 107, and TiAlN is adopted as the first oxygen barrier layer. These laminated structures utilize the above-described manufacturing method suitable for forming a metal thin film or a metal nitride film, for example, a sputtering method or a vapor deposition method. Next, tungsten is filled in the through hole as a first conductive material by the same thin film forming method as described above.
[0078]
Thereafter, an etch-back process is performed until the surface of the interlayer insulating film 106 is exposed, so that the opening surface of the through hole and the insulating film surface are formed on the same surface (ST11). By this step, a structure as a tungsten plug was formed in which the side walls and the bottom surface were surrounded by the close contact layer 107 and the first oxygen barrier layer 108.
[0079]
Next, the layer structure of the ferroelectric capacitor C is formed in the same manner as in the first embodiment. In the present embodiment, since it is not necessary to connect a wiring layer to the lower electrode 111, the shape of the ferroelectric capacitor C can be formed by one etching using the TiAlN of the third oxygen barrier layer 114 as a mask.
[0080]
Thereafter, an interlayer insulating film 117 is formed and through holes H3 and H4 are provided, which is almost the same as in the first embodiment. At this time, the through hole H4 is formed so as to be located immediately above the through hole H2 which is a lower tungsten plug.
[0081]
The layer structure provided in the through holes H3 and H4 and the formation of the bit line B can be performed in the same manner as in the first embodiment.
[0082]
According to the second embodiment, the first hydrogen barrier layer 116, the second hydrogen barrier layer 132, and the third oxygen barrier layer 114 have the same advantages as the first embodiment.
[0083]
Further, according to the second embodiment, the second oxygen barrier layer 110 shields oxygen that diffuses from the ferroelectric layer 112 and the second interlayer insulating film 117 to a lower layer during direct manufacturing. The first oxygen barrier layer 108 also blocks oxygen flowing around the side 110 and traveling from the side to the through holes H1 and H2. Therefore, the first conductor 109 formed of tungsten which is easily oxidized is virtually completely protected from oxygen. Therefore, it is possible to prevent the resistance of tungsten from increasing due to the oxidizing action, and to provide a highly reliable ferroelectric memory.
[0084]
(Third embodiment)
The third embodiment of the present invention relates to a semiconductor device of the present invention, an electronic apparatus including a ferroelectric memory, and particularly to a personal computer.
[0085]
FIG. 7 is a perspective view illustrating a configuration of a personal computer 1000 according to the third embodiment. 7, the personal computer 1000 includes a display panel 1001 and a main body 1004 having a keyboard 1002. As a memory element or the like of a CPU substrate incorporated in the main body 1004 of the computer display device 1000, a structure according to the present invention or a semiconductor device manufactured by the manufacturing method according to the present invention, in particular, a dielectric memory is used. I have.
[0086]
According to the third embodiment, since the oxygen barrier layer is formed around the tungsten plug, the oxygen generated by the formation of the ferroelectric layer and the insulating film oxidizes the tungsten and increases the resistance, so that the conductive state is established. Deterioration is prevented, and a highly reliable semiconductor device and electronic device can be provided.
[0087]
In addition, according to the third embodiment, since a hydrogen barrier layer is provided, a highly reliable semiconductor device and electronic device that does not deteriorate the polarization characteristics by reducing the ferroelectric layer by hydrogen generated at the time of forming a tungsten plug can be provided. Can be provided.
[0088]
It should be noted that the present invention is not limited to the above-described embodiment, and can be variously modified and applied without departing from the spirit of the present invention.
[0089]
For example, although the first hydrogen barrier layer 116 has a hydrogen barrier function using TiAlN, it may be replaced with another metal oxide or another insulating oxygen barrier layer. Further, the insulating oxygen barrier layer may be stacked with the hydrogen barrier layer to have both the oxygen barrier function and the hydrogen barrier function.
[0090]
Further, the order of lamination of the fourth oxygen barrier layer 131 and the second hydrogen barrier layer 132 may be reversed. Further, the third oxygen barrier layer 114 may be omitted.
[Brief description of the drawings]
FIG. 1 is a sectional view of a ferroelectric memory according to a first embodiment.
FIG. 2 is a sectional view of a manufacturing process according to the first embodiment (part 1).
FIG. 3 is a sectional view of the manufacturing process according to the first embodiment (part 2);
FIG. 4 is a sectional view of a ferroelectric memory according to a second embodiment.
FIG. 5 is a sectional view (1) of a manufacturing process according to the second embodiment.
FIG. 6 is a sectional view of the manufacturing process according to the second embodiment (part 2).
FIG. 7 is an exemplary perspective view illustrating an electronic device according to a third embodiment;
[Explanation of symbols]
B: bit line, C: ferroelectric capacitor, W: word line, 1a, 1b: ferroelectric memory, 100: substrate, 101: element isolation layer, 102: diffusion region, 103: gate insulating film, 104: side wall , 105 gate (word line), 106 first interlayer insulating film, 107 adhesion layer (Ti / TiN), 108 first oxygen barrier layer (TiAlN), 109 first conductor (W), 110 Second oxygen barrier layer (TiAlN), 111: lower electrode (Pt), 112: ferroelectric layer (SBT), 113: upper electrode (Pt), 114: third oxygen barrier layer (TiAlN), 115: resist, 116: first hydrogen barrier layer (AlOx), 117: second interlayer insulating film, 121, 123: adhesion layer, 122: wiring layer (AlCu), 131: fourth oxygen barrier layer (TiAlN), 132: second water Barrier layer (IrOx), 133 ... second conductive material (W), 141 ... fifth oxygen barrier layer, 142 ... wiring layer (AlCu), 143 ... sixth oxygen barrier layer

Claims (13)

A first barrier layer having conductivity for preventing diffusion of gas components is provided in a through hole provided in an interlayer insulating film formed on the lower ground,
A semiconductor device, comprising: a second barrier layer having an insulating property for preventing diffusion of a gas component, provided at an interface between the base surface and the interlayer insulating film and outside the through hole. An interlayer insulating film having a through hole formed on the lower ground,
A first oxygen barrier layer formed on at least the through hole wall surface and the bottom surface and having conductivity to prevent diffusion of oxygen;
A conductive material filled in the through hole. Conductivity for preventing diffusion of hydrogen, which is formed at least between at least one of the wall surface and the bottom surface of the through hole and the first oxygen barrier layer, or between the first oxygen barrier layer and the conductor. The semiconductor device according to claim 2, further comprising a first hydrogen barrier layer having: 4. The semiconductor device according to claim 2, further comprising an insulating second oxygen barrier layer formed between the base surface and the interlayer insulating film and surrounding the outside of the through hole. 5. 5. The semiconductor device according to claim 2, further comprising a second hydrogen barrier layer having insulating properties formed between the base surface and the interlayer insulating film and surrounding the outside of the through hole. 6. Semiconductor device. Providing a through hole in the interlayer insulating film formed on the lower ground,
Forming a first oxygen barrier layer having conductivity to prevent oxygen diffusion on at least the through hole wall surface and bottom surface;
Filling the through-hole with a conductive material. At least one of an interface between the wall surface and the bottom surface of the through hole and the first oxygen barrier layer or an interface between the first oxygen barrier layer and the conductor has a conductivity that prevents diffusion of hydrogen. The method of manufacturing a semiconductor device according to claim 6, further comprising: forming a hydrogen barrier layer. Forming a second oxygen barrier layer having an insulating property at an interface between the base surface and the interlayer insulating film;
8. The method of manufacturing a semiconductor device according to claim 6, wherein in the step of providing a through hole in the interlayer insulating film, the through hole is formed so as to communicate with the second oxygen barrier layer. Forming a second hydrogen barrier layer having an insulating property at an interface between the base surface and the interlayer insulating film;
9. The method of manufacturing a semiconductor device according to claim 6, wherein in the step of providing a through hole in the interlayer insulating film, the through hole is formed so as to communicate with the second hydrogen barrier layer. 10. A ferroelectric memory comprising the semiconductor device according to claim 1, wherein the base surface is formed by a part of a ferroelectric capacitor. 10. A ferroelectric memory formed by the method for manufacturing a semiconductor device according to claim 6, wherein the base surface is formed by a part of a ferroelectric capacitor. 12. The ferroelectric memory according to claim 10, wherein a third oxygen barrier layer having conductivity is provided on at least one of an upper electrode and a lower electrode constituting the ferroelectric capacitor. An electronic apparatus comprising the ferroelectric memory according to claim 10.

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